if you plan on slowmo, go 720_60p.
otherwise, shoot 1080_30p. i don't know what your edits look like, but i've found it very useful shooting 1080 HD for delivery in 480 SD. it allows me to reframe or zoom in on those long shots of the ceremony, giving me alternate 'shots' or angles to intercut the otherwise boringly long documentary-style coverage when i'm trying to create a shorter highlight reel. it also gives you a bit better color and lowlight sensitivity.
as for memory, i've been fine with 2 x 16gb cards, and usually fill both up to about 80%. i always have another 8gb card in the bag in case i need to shoot more, but haven't had to use it yet. and i'm shooting mostly documentary style where i have to capture the main events in their entirety, and then i fill up the cards with lots of broll to use in the short and sweet highlight reel.
otherwise, shoot 1080_30p. i don't know what your edits look like, but i've found it very useful shooting 1080 HD for delivery in 480 SD. it allows me to reframe or zoom in on those long shots of the ceremony, giving me alternate 'shots' or angles to intercut the otherwise boringly long documentary-style coverage when i'm trying to create a shorter highlight reel. it also gives you a bit better color and lowlight sensitivity.
as for memory, i've been fine with 2 x 16gb cards, and usually fill both up to about 80%. i always have another 8gb card in the bag in case i need to shoot more, but haven't had to use it yet. and i'm shooting mostly documentary style where i have to capture the main events in their entirety, and then i fill up the cards with lots of broll to use in the short and sweet highlight reel.